News

Shimmer Develops New Foot Sensor Algorithm

Boston, 22nd September 2017 - Shimmer has developed an algorithm to obtain mobility data from a Shimmer3 sensor (accel + gyro) placed on a shoe. This algorithm is based on state of the art wearable sensor/biomechanics research and has already been tested on a young, healthy data-set in order to obtain normative standards to compare metrics to.

This algorithm is ideal for applications in the area of sensors embedded into shoes, or applications that could be used for remote monitoring or supervised monitoring, such as in a clinic or care-home.

The below information gives an overview of the algorithm, as well as data vizualizations for the normative data that has been collected to date:

Algorithm Summary

The Shimmer foot sensor algorithm has three levels of metrics:

Variable Type

Metric

Description

Temporal

Stride time

The time between foot strike on one foot to the next foot strike on the same foot. Represents one full gait cycle.

Kinematic

Sagittal foot angle

Sagittal plane foot angle during the gait cycle. Zero angle represents the angle of the foot during foot flat. Positive values represent a rotation with the toes going upward and negative represents a rotation with the heels going upward.

Sagittal foot angle

Frontal plane foot angle during the gait cycle.

Spatial

Stride distance

The distance from one foot placement to the next foot placement with the same foot

Data Visualizations

Stride time below:

Sagittal foot angle

Frontal Foot Angle

Anterior/ Posterior foot Velocity

Stride Distance

Normative gait data was obtained with 30 (16 female / 14 male) participants who performed twenty 12m walking trials each. You can find the normative data from these 30 participants in the table below:

Feature

Unit

Mean

Max

Min

SD

Stride time

Sec

1.08

1.28

0.91

0.09

Peak sagittal foot angle

Deg

1.37

1.79

0.96

0.17

Min sagittal foot angle

Deg

-65.1

-30.9

-90.0

10.6

Max frontal foot angle

Deg

14.3

44.2

0.0

12.0

Min frontal foot angle

Deg

-13.1

0.0

-43.3

11.1

Peak AP foot velocity

m/sec

4.77

6.1

3.35

0.48

Stride length

m

1.37

1.79

0.96

0.17

Normalized stride length

m/cm

0.0113

0.0165

0.0074

0.0018

Watch this page because over the coming months, Shimmer is going to publish normative data with a healthy older adult population as well as a mobility limited elderly population.

If you are interested in this type of solution, please do not hesitate to contact us directly for more details.